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2018 F-150 Battery Draining Overnight - Help!

0

Mark S. · rep 0 · May 25, 1:34 AM · 1 replies · solved · Question

Vehicle: 2018 Ford F-150 Lariat

My 2018 Ford F-150 Lariat, 3.5L EcoBoost, has been having a persistent battery drain issue. I replaced the battery about 6 months ago, thinking that was the problem, but it keeps happening. If I leave it overnight, especially in colder weather, it's dead in the morning. I have to jump it almost every day. It's really frustrating.

I've checked for obvious things like lights left on, but everything seems off. Could it be a module not shutting down? I'm not sure where to even start looking for a parasitic draw. Any ideas on common culprits for these trucks?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 1:34 AM

0

ClearTheCode admin answer:

  1. Perform a Parasitic Draw Test:
    • Ensure all accessories are off, doors closed, and the vehicle has been asleep for at least 30 minutes (modules can take time to power down). For safety, disconnect the negative battery cable. Connect a multimeter in series between the negative battery post and the negative battery cable (set to Amps). A normal draw is typically under 50mA (0.05 Amps). If higher, proceed to step 2.
  2. Identify the Source:
    • While the multimeter is connected and showing a high draw, start pulling fuses one by one from both the under-hood and interior fuse boxes. Watch the multimeter reading. When the draw significantly drops, you've found the circuit causing the issue. Common culprits on F-150s include the HVAC blower motor resistor (especially if it was recently replaced or has issues), door modules, the SYNC/APIM module, or even a faulty Body Control Module (BCM).
  3. Causes: Parasitic draws are often caused by a module not "going to sleep" properly, a short in a circuit, or a component (like a light or relay) that's constantly drawing power.
  4. When to See a Shop: If you can't identify the specific circuit, or if the draw persists after addressing a suspected component, it's best to consult a professional. Diagnosing parasitic draws can be time-consuming and requires specialized knowledge, especially if it points to an internal module fault or complex wiring issue. A shop can use more advanced diagnostic tools to pinpoint the exact component or wiring fault.
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